Question 1

Which of the following resonance structures is the most stable for the allyl cation ($$CH_2=CH$$-$$CH_2$$^+$$)?

Accepted Answer

$$CH_2=CH$$-$$CH_2$$^+$$

Question 2

Which of the following is the correct order of alkene stability from least to most stable?

Accepted Answer

ethene \u003c monosubstituted \u003c disubstituted \u003c trisubstituted \u003c tetrasubstituted

Question 3

Which of the following dienes will absorb UV light at the longest wavelength ($$\lambda_{max}$$)?

Accepted Answer

conjugated diene

Question 4

When 1,3-butadiene reacts with HBr at low temperature, which product is favored?

Accepted Answer

1,2-addition product (kinetic)

Question 5

Which statement best explains why the trans-alkene is more stable than the cis-alkene?

Accepted Answer

Trans-alkenes have less steric strain due to substituents being farther apart.

Question 6

Which of the following is NOT an allowed resonance arrow movement?

Accepted Answer

Pi bond to lone pair

Question 7

In the Diels-Alder reaction, which diene conformation is required for the reaction to occur?

Accepted Answer

s-cis conformation

Question 8

Which of the following dienophiles will react fastest in a Diels-Alder reaction?

Accepted Answer

$$CH_2=$$CHCN$$

Question 9

Which product is the thermodynamic product in the addition of HBr to 1,3-butadiene?

Accepted Answer

1,4-addition product

Question 10

Which of the following best describes the molecular orbital interaction in a conjugated diene?

Accepted Answer

Four p orbitals combine to form four molecular orbitals, two bonding and two antibonding.

Question 11

Which of the following statements about resonance structures is TRUE?

Accepted Answer

Resonance structures with negative charges on electronegative atoms are more stable.

Question 12

Which of the following is the most stable carbocation?

Accepted Answer

tertiary carbocation

Question 13

Which of the following is the correct order of increasing $$\lambda_{max}$$ for the following compounds: cyclohexene, 1,3-cyclohexadiene, benzene?

Accepted Answer

cyclohexene \u003c 1,3-cyclohexadiene \u003c benzene

Question 14

Which of the following best explains why conjugated dienes are more stable than isolated dienes?

Accepted Answer

Conjugated dienes have more resonance stabilization due to delocalized electrons.

Question 15

Which of the following is a correct statement about the stereoselectivity of the Diels-Alder reaction?

Accepted Answer

A trans-dienophile gives a trans-cyclohexane product.

Question 16

Which of the following is the major product when 1,3-butadiene reacts with HBr at high temperature?

Accepted Answer

1,4-addition product

Question 17

Which of the following statements about the Diels-Alder reaction is FALSE?

Accepted Answer

Electron-donating groups on the diene decrease its reactivity.

Question 18

Which of the following best describes the effect of electron-withdrawing groups (EWGs) on the reactivity of dienophiles in the Diels-Alder reaction?

Accepted Answer

EWGs increase the reactivity of dienophiles.

Question 19

Which of the following is the correct product of a Diels-Alder reaction between 1,3-butadiene and ethene?

Accepted Answer

cyclohexene

Conjugated Dienes, Resonance, and Diels-Alder Reactions: Study Notes

Study Guide - Practice Questions